Geologic Plate: Supplement 1 from "The geology of a portion of the Repetto Hills" (Thesis)

Description

The area under consideration is located in what is known as the Rapetto Hills. It is located in the city limits of Los Angeles, and may be reached by going out North Broadway to Mission Road. From Pasadena the area is reached by way of Huntington Boulevard. The area is approximately six square miles in size. The base maps used were taken from the Alhambra, Los Angeles, Altadena, and Glendale sheets. In parts of the area it is quite solidly built up with homes, in other parts a little farming is attempted, mostly of barley and oats. Some of the homes, especially in the northern part are very nice, but the majority of them evidently belong to a very poor class of people. Lincoln High School is located in the extreme western part of the area near the intersection of North Broadway with Mission Road. The purpose of the investigation was to determine the geological formations and structure of a limited area in order to prepare a senior thesis as a partial fulfillment of the requirements for graduation. The base maps used were excellent Los Angeles County ones, with a scale of 2000 feet to the inch. Locations of outcrops, contacts, and the like were chiefly by topography, but in some cases the Brunton compass was used for purposes of location. The work was carried out completely on foot as a car was not available for the author. The nature of the country was such that it was extremely difficult to walk the contacts, and it was necessary to rely on roadcuts almost exclusively. There has been several previous reports issued on this area. One of these is U.S.G.S. Bulletin 309. This bulletin only shows the geology in a very rough way, and is more of a hinderance than a help. Eaton has also issued in the "Bulletin of the American Association of Petroleum Geologists" a paper on the "Geology of the Los Angeles Basin". This deals with the geology of the area which was undertaken in an even rougher manner than Bulletin 309. When the field work was nearing a close the author found out that C.L. Gazin, J.W. Daly, and M.H. Sperling, of the Institute, had previously mapped most of the area undertaken. Reference to Gazin's paper was made in order to use the same formational names, and thus avoid needless confusion. The paper by Daly and Sperling has not been examined by the author.

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